Not all soils are created equal — and that is crucial for your construction project

When excavating foundation pits, pipeline trenches or road surfaces, the question sooner or later arises: Where does the soil go? And above all: How is it legally classified?

A quick note upfront: since 1 August 2023, Germany has officially introduced a new, nationwide classification system — the so-called Substitute Construction Materials Ordinance (EBV), part of the broader Mantelverordnung. It replaces the former Z-values with new categories such as BM0, BM F1, BM F2 and BM F3. We will cover this new system in detail in a separate article.

In practice, however, the Z classification remains firmly established across the industry — it has been used by site managers, project engineers and waste disposal professionals for decades. This article therefore focuses on a specific question: What does Z2 actually mean? — and what does it mean in practice for your construction project.

What is the Z classification?

The Z classification is part of the "Decree on the Recycling of Excavated Soil and Construction Waste", commonly referred to as the Construction Waste Decree. It provides the legal framework for classifying excavated material according to its pollutant content — and determines whether that material may be recycled, treated, or must be sent to landfill.

The key classification levels are:

• Z0 — uncontaminated soil material, directly reusable
• Z1.1 — slightly contaminated material, still recyclable
• Z1.2 — moderately contaminated material, recyclable under specific conditions only
• Z2 — heavily contaminated, not directly recyclable, subject to landfill disposal

What exactly does Z2 mean?

The classification Z2 designates heavily contaminated soil that exceeds the permissible pollutant thresholds for direct reuse. Z2 material is therefore generally subject to landfill disposal — unless it is subjected to an appropriate treatment or immobilisation process.

Typical characteristics of Z2 soils:

• The soil contains significantly elevated pollutant concentrations, for example due to prior industrial use, brownfield sites or contaminated land.
• Pollutant levels exceed the thresholds of the Z1.2 classification and require special handling measures.
• Common contaminants include organic pollutants, heavy metals or mineral oil compounds at elevated concentrations.
• Direct reinstatement without prior treatment is not permitted without specific regulatory approval.

Z2 material presents a considerable challenge for many construction companies — generating both high disposal costs and significant logistical complexity.

How is the Z2 classification determined?

Classification is established through an analytical investigation of the excavated material. This involves sampling in accordance with LAGA PN 98, followed by analysis in an accredited laboratory.

Parameters tested include:

• Heavy metals (e.g. lead, cadmium, mercury, arsenic)
• Polycyclic aromatic hydrocarbons (PAH)
• Mineral oil hydrocarbons (MOH)
• BTEX compounds (benzene, toluene, ethylbenzene, xylene)
• pH value, electrical conductivity, sulphate, chloride

Only when the analytical results clearly confirm that Z1.2 threshold values have been exceeded is the material assigned to the Z2 category — with all the corresponding consequences for disposal and potential treatment.

What happens with Z2 soil material?

Z2 material may not be directly reused on a construction site. Depending on the material's composition and pollutant profile, the following options exist:

• Landfill disposal at a licensed special waste facility
• Immobilisation and treatment — e.g. by binding contaminants into a carrier matrix to permanently reduce their mobility
• Processing into Liquid Soil — under certain conditions, even Z2 material can be treated and safely reused within a Liquid Soil application, provided that pollutants are reliably immobilised in the process

At RMS Remake Soil GmbH, we advise you on which solution is appropriate for your specific material — and assess together with our laboratory partners whether technical and regulatory reuse is feasible.

Benefits of professional Z2 treatment over direct landfill disposal

• Significant cost savings compared to special waste landfill disposal
• Resource conservation through potential material recovery
• Legally compliant solution with full documentation trail
• Reduction of truck movements and CO₂ emissions
• Mitigation of liability risks through correct classification and proper disposal

When is Z2 relevant for your project?

The Z2 classification becomes relevant whenever you are working on previously contaminated or industrially used sites — for example:

• Sewer or pipeline construction
• Excavation pits and earthworks projects
• Demolition and remediation of contaminated sites
• Road construction and terrain modelling

RMS supports you with sampling, analysis and legally compliant classification — and where possible, with the economic recovery of your Z2 material.

Conclusion: Z2 — not automatically a one-way ticket to landfill

A Z2 classification does not automatically mean the end of the material's useful life. With the right analysis, expert advice and modern treatment methods, even heavily contaminated material can be handled safely and in full regulatory compliance — and in many cases at least partially recovered, rather than disposed of at significant cost.

In our next article, we take a closer look at the new nationwide BM classification system — and explain how BM0, BM F1, BM F2 and BM F3 relate to the familiar Z-values.

Would you like to know how your Z2 material can be handled?

We help you with classification, laboratory analysis and legally compliant disposal or recovery — professionally competent, reliable and sustainable.